In rope hoists, the rope drum is driven by an electric motor via interposed reduction gearing. The difficulty in this case consists in mounting the rope drum in such a way that alignment errors between the various bearings for the rope drum and the gearing are avoided as far as possible in order to avoid distortions and resulting increased wear of the bearings. This is not without its problems, because the rope drum has a considerable length and a considerable mass, so that the alignment of the bearings present at the ends cannot be easily produced with the required precision.
A further criterion is the number of components which are necessary for the drive and the mounting. Here, considerable attention has to be paid to the type of mounting of the rope drum, which for reasons of weight is tubular.
DE 12 05 247 B discloses a rope hoist whose rope drum contains a welded-in conical flange disk at one end, a tubular bearing journal being welded in place in the inner bore of the flange disk. The bearing journal in turn forms the output shaft of gearing, and the output gear of the reduction gearing sits on this output shaft in a rotationally locked manner. Located between the output gear and the rope drum is a rolling-contact bearing, which is accommodated in a bearing seat arranged in the frame of the rope hoist.
Since, in this design, the bearing journal, which is at the same time the output shaft of the gearing, cannot be separated from the rope drum, assembly of the rope hoist is extremely complicated. In addition, manufacture of the rope drum is expensive, for the flange disk welded to the bearing journal must first of all be welded into the rope drum. Only after that may the bearing journal be machined in order to produce the bearing seats. Producing the bearing seats before the welding in place would on no account result in the required precision. Slanting of the bearing seats of the bearing journal at least relative to the axis of the rope drum would be unavoidable, a factor which would cause enormous distortions in the gearing.
DE 438 528 C shows a rope hoist in which the rope drum is provided with an integrally cast hub, which is supported on the drum wall via spokes. Coaxially to this hub, the rope drum is provided with a recess, into which a cup-shaped internal gear is inserted. On the side of the drum hub, the internal gear merges into a disk-shaped base, from which a tubular extension protrudes. The hub and tubular extension are connected to one another via seats, so that the mounting of the drum is effected via the tubular extension of the internal-gear arrangement and the hub.
In this arrangement, the gearing output shaft, which carries a pinion meshing with the internal gear, is therefore separate from the drum mounting.
Since the internal gear is fastened by means of screws which are screwed into the end face of the rope drum, the rope drum must be relatively thick-walled, a factor which needlessly increases the weight of the rope drum. In addition, assembly and manufacture of the rope drum in this known solution is expensive.
DE 24 48 457 A1 shows a rope hoist in which multistage gearing is arranged in the interior of the rope drum. A bearing race forms the closure of the gearing at the end face of the rope drum, this bearing race being inserted into the rope drum and being rotationally locked by means of dowel pins, which pass radially through the drum. The race is mounted on an extension of the gearbox by means of a ball bearing. Alignment errors of this bearing seat, relative to the gearing in the interior of the rope drum, either load the bearing seat or lead to incorrect positions of the gears in the interior of the rope drum and thus to increased wear.
Against this background, the object of the invention is to provide a rope hoist in which a lightweight rope drum can easily be produced and in which no separate bearing points are necessary for the output shaft and the drum mounting.
In the novel solution, use is made of the fact that the rope drum must in any case be machined by turning. In this connection, locating seats which are coaxial to the outside of the rope drum can be produced on both front ends. These locating seats serve to locate end plates, which carry bearing journals. This ensures that the axes of the bearing journals are largely aligned both with one another and with the axis of the rope drum. One of the bearing journals is at the same time designed in such a way that it constitutes the output shaft of the reduction gearing. In this way, the mounting of the output shaft of the gearing at the same time becomes the mounting of the rope drum, a factor which makes additional bearings on the gearing side and compensating devices in the drive shaft unnecessary.
Since the end plate is inserted merely into the locating seat, greatly simplified assembly results. The gearing, with the output shaft and the gears, can be ready assembled and constitutes a comparatively light unit assembled at the works. In this case, no heavy or unwieldy rope drum impairs the assembly of the gearing, which can readily be checked without rope drum for operability and proper bearing play.
For the further assembly, it suffices to insert this preassembled gearing unit with the end plate sitting thereon for the rope drum into the latter and to secure it in the rope drum by means of the radially running fastening screws. Securing the end plate in the drum in this way permits the use of a rope drum whose wall thickness is dimensioned solely from the point of view of loading by the rope and is not needlessly enlarged on account of the use of screws screwed into the end face. Furthermore, the rope drum in the novel rope hoist is a simple tubular structure, on which no sensitive bearing journals project, as is partly the case in the prior art.
In addition, the radially running fastening screws for the end plate have the advantage of easy accessibility and they require no additional construction space between the rope drum and the adjacent gearbox wall.
The locating seat is preferably a recess, consisting of a cylindrical surface and an annular shoulder. If this annular shoulder is located in the interior of the rope drum, it is optimally protected against damage during transport. The annular shoulder, together with the cylindrical surface, forms a very good means of exactly centering the end plate in order to avoid wobbling runout and radial runout of the output shaft relative to the drum axis and the other bearing journal.
Assembly is further simplified if the output gear is profile-interlocked with the output shaft. As a result, simple slip-on attachment, which requires no especially large assembly force, is possible.
An especially robust construction is obtained if the gearbox is an essentially one-piece hollow formed part, in which the two end walls and the side-wall arrangement are connected to one another in one piece, the requisite bearing seats being accommodated in the end walls. For the purpose of assembly, an opening is contained in the side-wall arrangement in the region of the bearing seats for the output shaft, and the output gear sitting on the output shaft can be inserted through this opening.
In the novel rope hoist, the drive motor preferably sits outside the rope drum. Standard motors may therefore be used, and the cooling of the motor is not impaired by the surrounding rope drum and the air gap between motor and rope drum.